Think of it this way, if you try to cram a shirt, or any material, in a container there will still be air pockets, thus not complete conformity. Also, the molecules of cloth are locked and cannot freely move about and slide past each other. Vote: Solid

Addressing the original question, the ability to take the shape of the container is a poor way to characterize the state of matter. The distinction is made on the basis of inter-atomic/inter-molecular interactions. The strength of these interactions is manifest in macroscopic properties such as viscosity.